CHROME GLEAM 3C Jet Black Trivalent Chromium Plating Process

Transcription

1 Technical Data sheet CHROME GLEAM 3C Jet Black Trivalent Chromium Plating Process For Industrial Finishing Applications Regional Product Availability Description N. America Japan/Korea Asia Europe CHROME GLEAM 3C Jet is a decorative black trivalent chromium plating process developed to have an improved environmental profile compared to the existing hexavalent chromium acid based processes. Advantages Non-hazardous, decorative, black trivalent chromium plating process; safer than existing chromic acid-based processes Tolerates current interruption without producing dull deposits Uniform metal distribution and improved covering power Reduction of high current density burning Special graphite anodes are used in the CHROME GLEAM 3C Jet Process, resulting in long anode life and elimination of lead-containing sludge Bath Make-Up Bath Make-Up Metric Chemicals Required Range Recommended CHROME GLEAM 3C Make-Up: g/l 412 g/l CHROME GLEAM 3C Jet Starter 2*: ml/l 65 ml/l CHROME GLEAM 3C Wetting Agent: 3 9 ml/l 6 ml/l CHROME GLEAM 3C Complexor: 1 2 ml/l 1 ml/l CHROME GLEAM 3C Jet Additive: ml/l 15 ml/l *CHROME GLEAM 3C Jet Starter 2 is normally required only at the time of solution make-up. Bath Make-Up U.S. Chemicals Required Range Recommended CHROME GLEAM 3C Make-Up: oz./gal. 55 oz./gal. CHROME GLEAM 3C Jet Starter 2*: % v/v 6.5% v/v CHROME GLEAM 3C Wetting Agent: % v/v 0.6% v/v CHROME GLEAM 3C Complexor: % v/v 0.1% v/v CHROME GLEAM 3C Jet Additive: % v/v 1.5% v/v *CHROME GLEAM 3C Jet Starter 2 is normally required only at the time of solution make-up. Page 1 of 7

2 Bath Make-Up Procedure The order and method of preparation of the solution are very important. The following procedure should be followed exactly. Times listed are minimums. 1. Fill the clean plating tank with deionized water to approximately 60% of the final volume. With agitation, heat the solution to 60ºC (140ºF). 2. While maintaining the temperature and with agitation, slowly add 412 g/l (55 oz./gal.) CHROME GLEAM 3C Make-Up, making sure that the material is dissolving as fast as it is being added and that no undissolved material is on the bottom of the tank. [Note: The temperature of the solution will drop significantly during this addition. Reheat the solution to 60ºC (140ºF) to dissolve the CHROME GLEAM 3C Make-Up.] 3. Fill the tank to about 85% of its final volume with water and maintain a temperature of 50ºC (120ºF). Check the bottom of the tank to ensure that all of the CHROME GLEAM 3C Make-Up is dissolved. If not, maintain agitation until it is all dissolved. 4. With the temperature at approximately 50ºC (120ºF) and with agitation, add 80 ml/l (8% v/v) CHROME GLEAM 3C Jet Starter 2. Mix well. Maintain temperature for at least four hours. 5. Install the anodes previously fitted with the special titanium hangers. Ensure that all of the electrical connections are tight. Use PVC tape to cover any exposed copper anode busing at this time. 6. With the temperature at 32 C (90 F), and with agitation, add 6 ml/l (0.6% v/v) CHROME GLEAM 3C Wetting Agent, 1 ml/l (0.1% v/v) CHROME GLEAM 3C Complexor, and 15 ml/l (1.5% v/v) CHROME GLEAM 3C Jet Additive. 7. Add additional water to the working level. 8. Check the ph to ensure that it is within the range. If the ph is 2.8, the solution may be used at this time. Recheck the ph after about 3 4 hours and make a final adjustment (see paragraph on ph). If the ph is over 3.9, double check the bath volume and/or quantities of CHROME GLEAM 3C Make-Up added to ensure that they were correct. Reheat the solution to 50 C (120ºF) if a ph adjustment is performed. Cool to operating temperature. 9. Any high current density defect noted in the deposit at this time may require the use of a short electrolysis period ("dummy" time) for elimination. Page 2 of 7 Bath Operation - Metric Parameter Ranger Recommended ph Temperature C 32 C Current Density Cathode Anode 5-20 ASD 3-5 ASD 10 ASD 4 ASD Specific gravity @32 C C Anodes Special graphite Agitation Mild air agitation preferred Bath Operation - U.S. Parameter Ranger Recommended ph Temperature F 90 F Current Density Cathode Anode 5-20 ASD 3-5 ASD 10 ASD 4 ASD Specific gravity @90 F F Anodes Special graphite Agitation Mild air agitation preferred

3 Bath Maintenance Control of the solution requires monitoring ampere-hours (to replace the chromium, Replenisher 2 and CHROME GLEAM 3C Wetting Agent consumed by electrolysis), specific gravity (to compensate for solution losses), ph, and temperature. For optimum performance, additives need to be replenished at least once during each operating shift, or more frequently if the bath loading is high, e.g., greater than 0.75 amperes/liter (3 amperes/gallon). Additions of all components should be made on a regular basis. The solution is maintained by adjustment of those components consumed by electrolysis, followed by adjustment of the bath for loss of components consumed by drag-out. The other parameters to control are ph and temperature. The use of an ampere-hour meter for the replenishment of the components is recommended. Adjustment of components consumed by electrolysis can then be performed as described under CHROME GLEAM 3C Chrome Salt, CHROME GLEAM 3C Jet Replenisher 2 and CHROME GLEAM 3C Wetting Agent. Adjustment of the components consumed by drag-out can be performed by use of a hydrometer (covering the range of approx ); as described under CHROME GLEAM 3C Make-Up. Use of a log sheet to record ampere-hours, specific gravity, ph, temperature and additions is recommended. CHROME GLEAM 3C Make-Up The CHROME GLEAM 3C Make-Up supplies the chromium and materials necessary to promote solution conductivity. CHROME GLEAM 3C Make-Up is used at the time of solution make-up and for replenishment of solution losses by drag-out. CHROME GLEAM 3C Make-Up is replaced by measurement of the specific gravity of the solution, assuming an optimum specific gravity of As solution components are consumed, the specific gravity will drop and CHROME GLEAM 3C Make-Up must be added to restore the specific gravity to the optimum value of Measurement of specific gravity and subsequent additions of CHROME GLEAM 3C Make-Up must be made only after all other solution adjustments have been performed. Generally, an addition of 22 g/l (3 oz./gal.) of CHROME GLEAM 3C Make-Up will raise the specific gravity approximately 0.01 units. Additions of CHROME GLEAM 3C Make-Up to the plating tank should be made slowly. Air agitation should be used to ensure the complete dissolution of the material and that no undissolved material remains on the tank bottom. CHROME GLEAM 3C Make-Up is a green powder and contains chromium compounds. As such, dusting should be minimized and good industrial hygiene procedures should be followed when handling powders, for example, local exhaust, protective clothing and eye protection. CHROME GLEAM 3C Chrome Salt CHROME GLEAM 3C Chrome Salt is used to replace the chromium plated from the solution based on the number of ampere-hours consumed since the last addition. CHROME GLEAM 3C Chrome Salt should be added prior to any adjustment of the bath with CHROME GLEAM 3C Make-Up. CHROME GLEAM 3C Chrome Salt should NOT be used to adjust the specific gravity of the solution. Additions of CHROME GLEAM 3C Chrome Salt are added in a fashion similar to the CHROME GLEAM 3C Make-Up described earlier. It is important that the chromium concentration be maintained within the range specified. Generally, consumption of CHROME GLEAM 3C Chrome Salt will be 400 grams/1,000 ampere-hours (14 oz./1,000 ampere-hours) and should be added at least once every 4 ampere-hours/liter (15 ampere-hours/gallon) of operation. Page 3 of 7

4 CHROME GLEAM 3C Chrome Salt is a dark green powder and contains chromium compounds. As such, dusting should be minimized and good industrial hygiene procedures should be followed when handling powders, for example, local exhaust, protective clothing and eye protection. CHROME GLEAM 3C Jet Starter 2 CHROME GLEAM 3C Jet Starter 2 is required at the time of solution make-up and may be required to correct for component imbalances. CHROME GLEAM 3C Jet Starter 2 allows for the plating of chromium from the trivalent form. Chromium cannot be deposited without CHROME GLEAM 3C Jet Starter 2 present in the solution. CHROME GLEAM 3C Jet Starter 2 is maintained at an optimum concentration with regular additions of CHROME GLEAM 3C Jet Replenisher 2. Additions outside of the original solution make-up should be made only on the advice of Dow Electronic Materials. CHROME GLEAM 3C Jet Replenisher 2 CHROME GLEAM 3C Jet Replenisher 2 contains the necessary Starter 2 and darkening material that is consumed by electrolysis. Generally, the consumption of CHROME GLEAM 3C Jet Replenisher 2 will be 1,600 ml/1,000 ampere-hours (54 fl. oz./1,000 ampere-hours) and should be added at least once every 4 ampereours/liter (15 ampere-hours/gallon) of operation. Addition of CHROME GLEAM 3C Jet Replenisher 2 by amp-hour dosing is strongly recommended. CHROME GLEAM 3C Jet Additive CHROME GLEAM 3C Additive is added at make-up of the solution and is consumed by drag-out. Some of the CHROME GLEAM 3C Additive may be depleted during long idle periods or during heating of the solution. Maintain by adding 2 liters for every 45 kilograms (0.5 gallons for every 100 pounds) of CHROME GLEAM 3C Make-Up added. CHROME GLEAM 3C Wetting Agent CHROME GLEAM 3C Wetting Agent serves as a mist suppressant and improves deposit thickness distribution. Low CHROME GLEAM 3C Wetting Agent can result in the production of dark smudges in the deposit, particularly on surfaces facing upward. High concentrations are not harmful. A minimum concentration must always be maintained in the solution. The consumption of CHROME GLEAM 3C Wetting Agent is 55 ml/1,000 ampere-hours (2 fl. oz./1,000 ampere-hours) and should be added at least once every 4 ampere hours/liter (15 ampere-hours/gallon) of operation. CHROME GLEAM 3C Complexor CHROME GLEAM 3C Complexor assists in extending the current density range over which the chromium is deposited. It is used at the time of solution make-up, and usually, further additions are not required, except in special circumstances. Additions should be made only on the advice of Dow Electronic Materials. Page 4 of 7 ph The ph of the solution affects both the plating speed and the low current density coverage. Low ph produces the highest plating speeds but at the sacrifice of some low current density coverage. Conversely, high ph will result in slower plating speeds but with some improvement in low current density coverage. Adjustment of ph is made by the addition of concentrated hydrochloric acid to lower the ph or concentrated ammonium hydroxide to raise the ph. Additions of either hydrochloric acid or ammonium hydroxide will produce large changes in the ph when measured immediately after the additions. The solution will require approximately 2 4 hours to reach the "true" value of ph. For ph adjustment, add 2 ml/liter (2 gallons/1,000 gallons) of either hydrochloric acid or ammonium hydroxide to change the ph 0.1 units. ph should be maintained at

5 Temperature Optimum temperature is approximately 32ºC (90ºF). At temperatures much below this point, crystallization of solution components may occur on tank walls, filter, air agitation pipes, heating/cooling equipment or anodes. The temperature of the solution can affect deposit properties, such as low current density coverage and color; higher temperatures reduce coverage and produce darker deposits. Cooling of the solution may be required if tank current and duty cycles are high. Heating or cooling equipment may be fabricated from pure titanium (titanium alloys cannot be used). Titanium equipment within the plating tank should be situated behind the anodes and grounded to the anode circuit with resistance wire to prevent their becoming cathodic through bipolarity. If external heat exchangers are used for cooling, the solution should not be cooled to the point where solution components may crystallize in the piping. Immersion quartz electric heaters may also be used for heating the solution. The use of automatic temperature controllers is recommended. Current Density Thickness The cathode current density should be as low as possible in order to produce satisfactory work. This will reduce any requirement for cooling, rectifier capacity and optimize consumption of additives. Increasing current density may not result in improving deposit thickness, as cathode efficiency decreases with increasing current density. Although this will result in the production of good deposit thickness distribution (throwing power), thickness will be a factor of time rather than current density. Typically, chromium will be deposited at a rate of approximately µm/min. (microns per minute) [2 4 microinches (or µin.) per minute] regardless of the cathode current density. Agitation Mild and uniform air agitation is required to produce good deposit distribution and prevent solution and/or temperature stratification. Air lines can be fabricated from PVC pipe. Equipment Tanks Lead-lined or metallic tanks CANNOT be used. The tank lining must be made of plastic or rubber. Generally, linings suitable for nickel plating are suitable for trivalent chromium plating. Existing lined tanks that previously contained hexavalent chromium solution must be thoroughly cleaned prior to use in order to remove not only any hexavalent chromium but any lead that may have been absorbed in the lining. These linings should be thoroughly scrubbed, leached with slightly acidic sodium metabisulfite solution (to reduce hexavalent chromium) and then leached with dilute hydrochloric acid (to remove absorbed lead salts). Any residue remaining after leaching should again be scrubbed and the lining again leached with dilute hydrochloric acid. A less desirable choice to scrubbing and leaching is to use a drop-in plastic liner, however, the risk of damage to the liner and subsequent contamination of the trivalent chromium solution may not justify this option. Anodes The CHROME GLEAM 3C Jet Solution uses special graphite anodes fitted with titanium anode hangers designed to ensure good electrical contact. These hangers are available from Dow Electronic Materials. Sufficient anode area should be provided to allow for a maximum anode current density of 5 amp/ sq. dm (50 amp/sq. ft.), considering the maximum anticipated current to be used on the tank. A nominal 60 5 cm (24 2 inch) diameter anode has an effective area of 10 sq. dm (one sq. ft.). It is important that the top of the anode be BELOW the solution level at least 2.5 cm (one inch). Copper contamination can result from CHROME GLEAM 3C Solution dripping over exposed copper anode and cathode bus bars. The bus bars should be shielded Page 5 of 7

6 by covering and/or taping with PVC tape, for example. During plating, some objectionable compounds can form on the anode surfaces that may be noticeable if the anodes are removed during or immediately after the cessation of plating. So as to minimize any odors, anodes should not be removed for 30 minutes after the cessation of plating. Heating/Cooling In most circumstances, some heating will be required to allow the solution to reach the operating temperature. Once reached, little or no heating will be required. In some instances, where the current loading is high [e.g. >0.75 amps/l (3 amps/gal.)], cooling may be required. Heating equipment may be fabricated from quartz or pure titanium (alloys not allowed.) Internal cooling coils must be fabricated from pure titanium and situated behind the anodes in order to eliminate bipolar effects that may corrode the titanium. (See Temperature.) Rectifiers Generally, rectifiers with 6 9 volt capacity should suffice. However, 12 volt systems, with sufficient ampere capacity, will be more flexible. Ventilation Exhaust ventilation is required primarily to remove possible over-spray produced by the air agitation and in the event any objectionable gassing is produced at the anode or cathode surface. Metallic Contamination Metallic contamination of trivalent chromium plating solutions is much more of a factor than in hexavalent chromium plating solutions. The degree of contamination in trivalent chromium solutions that can lead to difficulty is similar to most bright nickel plating solutions. Frequent sources of contamination are parts lost from racks and inadequate rinsing after nickel. Electrolytic purification, in some cases, can be used to keep the impurities within tolerable limits and can be performed by plating at approximately 5 amp/sq. dm (50 amp/sq. ft.), using heavily nickel plated dummy (preferably corrugated) cathodes, until the contamination is eliminated. Contaminants are usually found together and may reinforce one another. For example, g/l zinc, 0.06 g/l iron, and g/l copper would be more harmful than the individual contaminant, although each element may be within tolerable limits. Therefore, it is important that metallic contamination is be minimized, so as to optimize trouble-free operation. Purification of the CHROME GLEAM 3C Solution can be accomplished by other means, such as ion exchange. Product Data For the specific Product Data values, please refer to the Certificate of Analysis provided with the shipment of the product(s). Associated Products CHROME GLEAM 3C Make-Up CHROME GLEAM 3C Chrome Salt CHROME GLEAM 3C Jet Starter 2 CHROME GLEAM 3C Wetting Agent CHROME GLEAM 3C Complexor CHROME GLEAM 3C Jet Additive CHROME GLEAM 3C Jet Replenisher 2 Page 6 of 7

7 Handling Precautions Before using this product, associated generic chemicals or the analytical reagents required for this control, consult the supplier s Material Safety Data Sheet (MSDS)/Safety Data Sheet (SDS) for details on material hazards, recommended handling precautions and product storage. CAUTION! Keep combustible and/or flammable products and their vapors away from heat, sparks, flames and other sources of ignition including static discharge. Processing or operating at temperatures near or above product flashpoint may pose a fire hazard. Use appropriate grounding and bonding techniques to manage static discharge hazards. CAUTION! Failure to maintain proper volume level when using immersion heaters can expose tank and solution to excessive heat resulting in a possible combustion hazard, particularly when plastic tanks are used. Storage Disposal Considerations Store products in tightly closed original containers at temperatures recommended on the product label. Dispose in accordance with all local, state (provincial) and federal regulations. Empty containers may contain hazardous residues. This material and its container must be disposed in a safe and legal manner. It is the user's responsibility to verify that treatment and disposal procedures comply with local, state (provincial) and federal regulations. Contact your Dow Electronic Materials Technical Representative for more information. Product Stewardship Customer Notice Dow has a fundamental concern for all who make, distribute, and use its products, and for the environment in which we live. This concern is the basis for our product stewardship philosophy by which we assess the safety, health, and environmental information on our products and then take appropriate steps to protect employee and public health and our environment. The success of our product stewardship program rests with each and every individual involved with Dow products from the initial concept and research, to manufacture, use, sale, disposal, and recycle of each product. Dow strongly encourages its customers to review both their manufacturing processes and their applications of Dow products from the standpoint of human health and environmental quality to ensure that Dow products are not used in ways for which they are not intended or tested. Dow personnel are available to answer your questions and to provide reasonable technical support. Dow product literature, including safety data sheets, should be consulted prior to use of Dow products. Current safety data sheets are available from Dow. For Industrial Use Only. This information is based on our experience and is, to the best of our knowledge, true and accurate. However, since conditions for use and handling of products are beyond our control, we make no guarantee or warranty, expressed or implied, regarding the information, the use, handling, storage or possession of the products, or the applications of any process described herein or the results sought to be obtained. Nothing herein shall be construed as a recommendation to use any product in violation of any patent rights. Contact: North America: Japan: (+81) Asia: (+852) Europe: (+41) Notice: No freedom from infringement of any patent owned by Dow or others is to be inferred. Because use conditions and applicable laws may differ from one location to another and may change with time, Customer is responsible for determining whether products and the information in this document are appropriate for Customer's use and for ensuring that Customer's workplace and disposal practices are in compliance with applicable laws and other government enactments. The product shown in this literature may not be available for sale and/or available in all geographies where Dow is represented. The claims made may not have been approved for use in all countries. Dow assumes no obligation or liability for the information in this document. References to Dow or the Company mean the Dow legal entity selling the products to Customer unless otherwise expressly noted. NO WARRANTIES ARE GIVEN; ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED. Page 7 of 7